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The article analyzes the influence of the season of the year on qualitative and quantitative sperm parametres of servicing bulls, it also considers the  structure of reasons for culling of ejaculates. The research was carried out on bulls of Holstein, Black Spotted, brown Swiss and Hereford breeds at the age of  2-6 years in OOO “Nizhegorodskoe” for breeding work”. Statistically significant influence of the month of the year on concentration and activity of spermium,  the ejaculate volume, the proportion of rejection of ejaculates that do not meet the requirements was established. The sperm concentration was 0.592 billion /  ml at the beginning of the year. In spring, there was an increase in concentration and a sharp jump in June to 0.886 billion / ml, then it gradually decreased. The  average volume of ejaculate at the beginning of the year was quite high 7.69-8.45 ml, in June there is a sharp decrease in volume, in subsequent months there  was a gradual increase in volume to 7.68 ml. The sperm activity parametres change slightly during the year. At the beginning of the year, sperm activity was  5.98 points, in March there is an increase to 6.33 points, and in July to 6.47 points. After July, there is a decrease in activity to 5.95 points. The month influence  on sperm concentration was 28.18 %, on the average volume of ejaculate - 19.73 %, on sperm activity - 6.36 %, on the number of frozen semen doses - 10.49 %.  The most intensive culling of native sperm occurs in winter-spring months - 16-18 %, in summer culling is reduced to 3-8 %. Thus, in June, the maximum number  of semen doses per a servicing bull was received - 887.4. The main reason for culling throughout the year was a low concentration of sperm in the ejaculate,  more than half of the culled ejaculates (54.3 %) had this cause, 26.6 % - low activity, 13.6 % - both defects at the same time, 5.5 % were culled for other reasons

THE INFLUENCE OF THE MONTH OF THE YEAR ON SPERM CULLING INTENSITY OF SERVICING BULLS